1. Field of the Invention
The present invention relates to a magnetic head apparatus for recording magnetic data in a recording layer having high coercive force and to a magnetic recording and reproducing apparatus provided with the same.
2. Description of the Related Art
Conventionally, a significant improvement in the areal density of magnetic recording media such as hard disks is achieved by, for example, reducing the size of magnetic particles constituting the magnetic recording layer, improving materials, or refining the process of a head. Furthermore, in recent years, a perpendicular magnetic recording and reproducing apparatus has come into widespread use in which the improvement in the areal density is achieved by magnetizing a recording layer in the direction perpendicular to the surface of the magnetic recording medium. In addition to this, a further improvement in the areal density is expected in the future.
Meanwhile, as both the size of recording bits and magnetic particles are reduced, thermal fluctuations are more likely to occur. Therefore, it is preferable that magnetic particles having high magnetic anisotropy energy and high coercive force are used as the material for the recording layer.
However, when magnetic particles having high magnetic anisotropy energy are used as the material for a recording layer, the coercive force of the recording layer becomes large, for example, more than 4 kOe. When saturation magnetic recording is performed, it is generally recognized that a recording magnetic field of approximately two times the coercive force is required. Thus, occasionally, the performance of a conventional magnetic head is not sufficient to saturate the magnetization of a recording layer. In other words, the recording and erasing of magnetic data is occasionally difficult to undertake.
In view of the above, a magnetic recording and reproducing apparatus is known (see, for example, Japanese Patent Laid-Open Publication No. 2001-250201) which includes a recording layer which is heated by irradiation with a beam to temporarily reduce the coercive force of the heated portion. A recording magnetic field is simultaneously applied to the heated portion to perform the recording of magnetic data.
However, the magnetic recording and reproducing apparatus provided with, in addition to a magnetic head, a head for irradiation with the beam has a complicated structure and it is therefore difficult to make the apparatus compact.
Furthermore, it is difficult to accurately irradiate a fine target recording portion with the beam and to accurately apply the recording magnetic field thereto.
In addition to this, in the recording layer, not only the portion irradiated with the beam but also the surrounding portion is heated by heat conduction. Further to this, since the temperature distribution of the heated portion and the recording magnetic field distribution of the magnetic head are not uniform, it is difficult to reliably reverse or erase the magnetization in desired target recording portions only. In other words, data recording with high accuracy and high quality is difficult to obtain.
Moreover, since the surroundings of a target recording portion are also heated, thermal fluctuations are therefore likely to be promoted.
Furthermore, in order to temporarily reduce the coercive force by heating, it is preferable to use, as the material for the recording layer, a material in which the coercive force significantly decreases as temperature increases. However, it is necessary to develop such a novel material. In addition to this, even when such a material is employed, thermal fluctuations are likely to occur when the environmental temperature increases.